At approximately 104 miles into a recent trip in our RV, while traveling at highway speed under cruise control, we noticed a strange odor. Almost at the same moment we immediately lost engine and braking power. The check engine light came on. We then noticed smoke coming from the engine compartment and noxious fumes had begun to enter the cabin area. After pulling to the side of the highway by use of the emergency brake, we were able to exit the vehicle. Flames could be seen coming from the engine bay and quickly engulfed the RV giving my wife, myself, and our dog only enough time to exit and get a safe distance away. The RV burned to basically nothing but the frame left.